Automatic visual field examination including fixation monitoring compensation

ABSTRACT

An illustrative embodiment of the present invention includes method and apparatus for determining locations in a test field at which a subject is able to perceive visual stimuli. The stimuli are presented on a test screen under control of a programmed automatic data processing system. The subject communicates with the data processing equipment via a subject response device and the system interprets the responses to alter the stimulus presentation regime dynamically while communicating feedback to the subject of correct or incorrect perception of each stimulus. Eye movement of the subject is monitored and compensated for in the presentation of the stimuli by other system apparatus which also communicates with the data processing equipment to continuously center the test field relative to the direction of gaze of the subject (which may not necessarily be the center of the test screen or a fixed point).

United States Patent Lynn et al.

1111 3,883,235 1*May 13, 1975 OTHER PUBLICATIONS Deugn, April I959, pages 24-30 On the Line of Sight".

[76] Inventors: John R. Lynn, l000l Preston Rd.,

Dallas 75230; George Tate Primary Examiner-Paul A. Sacher 4323 Brown Dallas Armrne A em or Firm-Cle Cantrell & Crisman Tex. 75219 g Notice: The portion of the term of this patent subsequent to Feb. 27, I990 [57] ABSTRACT has been disclaimed, An illustrative embodiment of the present invention includes method and apparatus for determining loca- [22] Filed 1973 tions in a test field at which a subject is able to per- {21} Appl. No.: 335,572 ceive visual stimuli. The stimuli are presented on a test screen under control of a programmed automatic data I i Apphcauon Data processing system. The subject communicates with the [63] Continuation-impart Of Ser. N0. l81,538, Sept. 17, data processing equipment via a subject response de- [971 31718386 vice and the system interprets the responses to alter the stimulus presentation regime dynamically while [52] US. Cl. 351/39 Communicating feedback to the Subject of Correct or [5 [1 Int. Cl A6Ib 3/02 incorrect perception of each stimulus. Eye movement [581 of Search 351/6 of the subject is monitored and compensated for in the 35]]39 presentation of the stimuli by other system apparatus which also communicates with the data processing {56] References cued equipment to continuously center the test field rela- ITE TA PATENTS tive to the direction of gaze of the subject (which may l,942,850 1/1934 Tillyer 351/24 not necessarily e th c nter of the test screen or a 2,374,854 5/l945 Feinblooms 351/24 fixed point). 3,317,268 5/l967 Oswold 1 351/23 )4 D 3,416,857 12/1968 Lookabaugh 351/39 x 39 Claims, 37 Drflwlng Flgures 3,421,498 l/l969 Gans 35l/24 X 3,450,466 6/l969 Streismyer i 1 35l/39 X 3,664,732 5/l972 Lynn 1 35l/23 X 3,7l8,386 2/l973 Lynn et al 35l/23 X 1* M l c r" FLECTlilll DlBlTAL i 5 iiii v mii ii srv MIIlL OG \I 1* war CONTROL ms Y 0011mm at l FIXAllflli POINT u f" *i i i llOlilTOil DIGITAL 1 I 1 1111111 56 1:306 3%,??? REGISTER 42 51 CUIIPUTER 11m INPUT 111111111 cmcuns 1%" RESPONSE FM lllPllI SWITCH ClRCUllS cmcmrs 1 O O o o o O o rout GENERATOR OUTPUT WANDE R D N A F T VA CL lF FIXATION COUNT OUT CALL FIXATION POINT MONITOR PROGRAM PAIENTEB RAY I 3 I575 SIIEET 02 OF 21 CALL INITIALIZATION PROCRAM READ INPUT DATA, FIND WHICII EYE BEING TESTED AND ADAPT TEST POINT SEOUENCE iTO EYE SELECT TEST POINT ICYCLIC TEST POINT COUNTER) COUNTS OUT WHEN ARRAY EMPTY IS DIGITAL FIXATION POINT MONITOR BEING USED POINT AT THRESHOLD FROM TEST ARRAY REMOVE TESTED PROGRAM TO MODIFY DATA TO INDICATE SPOT SEEN RESPONSE m EL R R 0 0 CALL BLIND SPOT MAP PROGRAM NO RESPONSE OR INCORRECT RESPONSE PROGRAM TO MODIFY TEST DATA TO INOIOATE SPOT MISSED IZTTENTED I 3 75 SHEET EBUF 21 4 BITS 6 BTTS qns 4 BTTS T] we ilsf 32 23 24 FTC5.4

% aus D0 AU An 2 M -I\.VID E A1 VAT w 0 N A .T 2. T0 Em s NI GD E DIE 0 0 OH O TG Rm Cc N "N 00 mrt R R05 A G VADM [IMP F L LR nU C N .U M m 2 Cu 2 O E r 91 Y N 0 m y W flu T 2 A) f. N Y Fm S TR Tl T I O E P al T 5 m m TN OE N VTU IL E0 N L O DIM P m8 R DI Tl vAAn GT N0 mm" n w \IL N W T T T M mm mmm E T 5 -,|mTTsn/ TT 7' 8" DA T ITICU T I NA DAME 0 N OR A] D VA IG [LA CL T N CL PG RD Lm ETDOH P W I L50 ELL C P IL AE SB mDuP CRDI N 6 5 0 0 2 2 FIG.

TITLE PATIENT DATA LEGEND PERFORMED BY COMPUTER PERFORMED BY I EXTERNAL L I EOU IPMENT PRESENT X TO l6 OUTPUT LINES PULSE CONTROL LINE 2 PATENTEO FIG 6 4 PULSE CONTROL LINE I am JOY BUFFER I IS RESPONSE WITHIN n SECTORS 0F WHERE IT 92 IMER? I OFF L {*L WORN L LL ZLJ EX IT TO MOOI F IOATION PROGRAM (BLOCK TO I PAINTED RAY I FIG. 7

SHEET LIMIT B OF DATA PO TESTED 1 SET TBB- B-4 REPLACE BRIGIITNESS WITH BRIOIITNESS JUST NT WAS YES OD RREOT .IOYSTICII RESPONSE PRESENT BSDF 21 IOS REPLACE DIN LIIIIT D OF DATA POINT RITII BRIOIITNESS VALUE B JUST TESTED SET IBB B+ 2 HAS B LIMIT OF THIS POI NT BEEN A I OR 3 THRESHOLD SET INTENSITY DATA IDB ON DATA POINT FOR NEXT TEST EXIT TO NEXT DATA POI NT NOT YET REAOI-IED OLOSE REMOVE DATA FOR THIS POINT FROII TEST ARRAY STORE IN OUTPUT ARRAY EXIT TO NEXT DATA POINT EXIT TO NEXT DATA POINT PATENTEI] HAY l 3l975 SHEET CB 8F 21 FIG. 8

TEsTTo BE NovEII TOA NEw RAY OR Is TIIIs FIRST ENTRY mm as.

TEsT YES CHOOSE NEXT RAY coNPIITE NEXT TEST FROM cuRRENT B.S. POINT EWRDWATE I26 CENTER FOR TEsT: MOVE FROM CENTER ALONG FLAG LAST RAY EsTARLIsNEIJ RAY FOR EINIsN (T28 COORDINATE vAEIII OUTPUT ERROR (EXTEND OFF EDGE 0R To SUPPRESS FURTHER F|XAT|0N PRINT FAULT R. TESTING T23 CALL IoYsTIcN RESPONSE FLAG NO MORE AND EXTERNAL EIIIIIPIIENT PoINTs To EXIT INTEREAcE PROGRAM RE TEsTEI) 0N TRIs RAY [30/ (IE. PRESENT TEsT sPoT To PATIENT) {I33 PEAcE cooRnINATE PLACE COORD'WE 0 sm usT 0F TEST m T J OUTPUT ARRAY TESTED IN IIAIN [I52 TEsT ARRAY E0R AccIIRATE 0F THRESHOLD NEAsIIRE BSFOUND EXIT TO CONTINUE IN 55 TEST FLAG NO MORE TESTS 0N THTS 34 RAY SHEET 070E 2T FIG. IO

I5 PLOT 0m SHORIIEIIEF TEsI IN 8mm VISUAL FIELD T0 DISPLAY FORM OF 8.5. DDRRESPDND TD PREDICTED CENTER COMPLETE VISUAL FIELD NITH ISDPTER DISPLAY TD BE DONE DATA IN VISUAL FIELD ISDPTER RECONPUTE uomzoum MERIDIAN or as BASED on TEST om: SET UP NEW nomzoum MERIDIAN TEST BASED ON THIS DATA REPRESENTATIVE RAY 2 LATER TEST RAYS PATIENT, DATE, LEGEND PAIENIED an 1 3197s 863 .235

SHEET EBUF 21 4 I4 24 34 44 REGISTRY OFRETINAL IMAGE mo DISPLAY HXATION a 1,5 2,5 3,5 4,3 scam mm FIXATION FIG. !3A

POINT M2 2.2 5,2 4,2 POINT AT CENTER OF scam |s,| 2,| a,| 4,|

RETINAL IMAGE H F 1 1 L 5 gm' REGISTRY OFRETINAL mm AND msmv l 113%"3 U Z E SCREEN WITH smmo i HXAHON POINT I -13mm \JJISPLAY scam Y HXATION POINT (GO0RDINATE WN CENTER or PUPIL AND CENTER POINT or PUPIL IMAGE 0mm AXIS 0F EYE JSCREEN (omscnou 0F cm) CENTER or P coaum L GURVATURE Y'mme) RADIATION FROM SOURCE wnmn ucuwumn m5 REFLECTED AT comm F" IG. I4

CURNEA A|R INTERFACE PATENTEBHAYWTHYS .883.235

SHEET 1 u u? 4 ex AND BY INPUT mom nxmou POINT MEASURING FIG. l9 DEVICE ML F'|C3.I7 06 A WRITE g z nxmnn ERROR COMPENSATION MESSAGE E 04 DESIRE 2 a q 292 g 03 29s YES g L; 0.2 TRANSLATE TEST FIELD E coonomms TO NEW 01 SCREEN COORDINATES 0 l x'- x+exu \0 20 30 Y Y+ 9Y0 ANGLE 0Q SINE ruucnou unm EXTRAPOLATION mom FIRST PART or SINE FUNCTION CHOOSE NEXT TEST POINT FIG. I6 257 [7 r mmgunmslsrs $883,235

sum 12 0F 21 F'ICB. 23A

ph gmggamslms 3,883,235

SHEET 13 OF 21 ENTER SELECT BRIGHTNESS LEVEL FROM STACK ,502

SELECT BASIC RAY 504 AT RANDOM TEST ALONG BASIC RAY J AND RECORD THRESHOLD POINT IF ONE IS DETECTED IS THIS RAYA QUAD EXTERNAL RAY OR A QUAD INTERNAL RAY EXTERNAL INTERNAL HAS FELLOW RAY BEEN TESTED HAVE ALL BASIC RAYS BEEN TESTED IS SEPARATION OF THRESHOLD POINTS OF THESE RAYS SIGNIFICANT SIG SET FLAG T0 INDICATE NEED FOR INTEROUAD TEST PROGRAM AND ADD POINTS TO INTEROLIAD TEST POINT STACK IS INTEROUAD TEST FLAG SET FIG. 25A

FATENTED HAY I 3I9T5 SHEET 1h OF 21 CALL INTERQUAD TEST PROGRAM IS SCOTOIIA TEST FLAG SET CALL SCOTOIIA TEST PROGRAM ARE ALL THRESHOLD POINTS ON THIS ISOPTER ACCEPTABLY CLOSE SELECT PAIR OF THRESHOLD POINTS HAVING IIIIDEST PERIMETRIC SEPARATION CALCULATE AND TEST ALONG I AND RECORD THRESHOLD INT HAVE SUFFICIENT NUMBER OF RAYS IN THIS OUADRANT BEEN TESTED MARK THIS OUADRANT CLOSED TO THIS ISOPTER TEST FIG. 25B

FATENTEDI-IAY I 3|9I5 883,235

SMEEI 15 OF 21 SIG YES

IS MAXIMUM SEPARATION BETWEEN N0 RESENT AND PRIOR ISOPTER GREATER THAN [N544 Z SETFLAG OF ISOPTER TEST COMPLETION A INITIALIZE FOR NEXT ISOPTER TEST 5-528 YES IS MINIMUN SEPARATION BETWEEN PRESENT AND PRIOR ISOPTER LESQS g ALL REQUIRED NORMAL,INTEROUAD AND YES SCOTDMA TESTS FOR 1 PRESENT BRIGHTNESS SELECT BRIGHTNESS CALL INTERISOPTER LEVEL INTERMEDIATE STATIC TEST THE LEVELS USED FOR PROGRAM TESTING PRESENT AND PRIOR ISOPTER AND N545 STORE IN BRIGHTNESS LEVEL STACK ALL BRIGHTNESS LEVELS IN STACK BEEN TESTED ANY SCOTOMAS FOUND VERIFY SCOTDMA SET FLAG TO INDICATE NEED FOR SCOTOMA TEST PROGRAM AND ADD POINTS TO SCOTOMA TEST POINT STACK FIG. 25C

PATENTED RAY I 31975 3,883 .235

SHEET 1B0? 21 ENTER I SELECT AN INTEROUAO AREA NEEDING TESTING 602 SELECT PAIR OF THRESHOLD POINTS HAVING WIDEST PERIIIETRIC SEPARATION /604 CALCULATE AND TEST ALONG LS, BEGINNING ON STARTING CIRCLE ON SAME SIDE OF INTEROUADRANT LINE AS POINT CLOSEST TO FIXATION PO|NT,AND

RECORD THRESHOLD POINT 606 ARE CLOSE TEST OF ALL THRESHOLD YES ms INTEROUAD POINTS ACCEPTABLY AREA AND STORE CLOSE AND NUMEROUS RESULTS 610 FIG. 26

FIITENTED RAY I 3575 1.883.235

SHEET 178F231 SELECT A SCOTOIIA NEEOING TESTING SELECT A POINT FROM SCOTOMA TEST POINT STACK BEEN TESTED FOR THE POINT 2 TEST ALONG AN UNTESTED SELECT PAIR OF BOUNDARY PRINCIPAL RAY AND RECORD POINTS HAVING WIDEST BOUNDARY POINT PERIHETRIC SEPARATION l SSO CALCULATE AND TEST ALONG LS AND RECORD BOUNOING POINT ARE ALL BOUNDARY POINTS AOCEPTABLY CLOSE FLAG NO MORE TESTS ON THIS SCOTOMA AND STORE RESULTS FIG. 27

FATENTED HAY I 3I975 3,883 .235

SHEET 18 OF 21 CALCULATE COORDINATES 640 OF STATIC POINTS TO TEST BETWEEN ISOPTERS SUCH THAT POINTS ARE AT LEAST Z/2 DISTANCE FROM EACH OTHER AND FROM ISOPTERS SET BRICHTNESS LEVEL EOUAL TO THAT OF F542 BRICHTER ONE OF ISOPTERS BOUNDINC TEST AREA SELECT POINT AT RANDOM QSIIIRHAPPLY SPOT AT THAT REMOVE POINT mom TEST ARRAY WAS SPOT SEEN PLACE POINT IN LIST FOR SCOTOHA TEST FIG. 28 

1. An automatic machine implemented process for testing the visual field of a subject comprising the steps of: establishing a test field positioned relative to a predetermined point on a test screen; determining, under machine control, the instantaneous location of the direction of gaze of the subject relative to the predetermined point; translating the test field relative to the predetermined point on the test screen when the direction of gaze is not at said predetermined point to reposition the test field relative to the direction of gaze the same as the position of the test field relative to said predetermined point when the test field was initially established; presenting, on the test screen, under machine control, test stimuli of selected stimulus value at preselected locations in the test field; and determining whether the subject percieved the test stimuli.
 2. A process as in claim 1 wherein said test stimuli are presented under machine control in a sequence not predictable by the subject.
 3. A process as in claim 1 further including the steps of supplying an indication of correct perception to the subject if the subject correctly perceives a test stimulus and supplying an indication of incorrect perception if the subject incorrectly indicates perception of the stimulus.
 4. A process as in claim 1 wherein the subject indicates perception of a stimulus by operating a manual device.
 5. A process as in claim 1 wherein a determination that the subject perceived a stimulus is made by monitoring a change in the evoked cortical potentials in the occipital center.
 6. A process as in claim 1 wherein a determination that the subject perceived a stimulus is made by detecting movement of the subject''s eye in the direction of the test location at which the stimulus was perceived.
 7. A process as in claim 1 wherein a determination that the subject perceived a stimulus is made by monitoring a change in the diameter of the pupil.
 8. A process as in claim 1 wherein said test stimuli are spots of light presented at selected test locations which are stationary in said test field.
 9. A process as in claim 8 further including the steps of presenting, under machine control, additional momentary spots of light of varying stimulus value at said selected test locations, and determining the stimulus values at which the particular spots of light are perceived by the subject.
 10. A process as in claim 9 wherein the stimulus value of an additional momentary spot of light to be presented at a particular test location is computed in response to the subject''s history of perception response at the test location in question, such that the threshold value of stimulus perceived at each selected test location in the test field is detected.
 11. A process as in claim 8 further including the step of displaying under machine control, the threshold value of the stimulus at each selected location.
 12. A process as in claim 1 wherein the step of determining, under machine control, the instantaneous location of the direction of gaze of a subject is performed by monitoring the relative location, on an image of the eye pupil, of the image of a point source of radiation.
 13. A process as in claim 12 wherein the point source of radiation is located effectively at infinity.
 14. A process as in claim 1 wherein the step of determining, under machine control, the instantaneous location of the direction of gaze of a subject is performed by monitoring the changes in the horizontal and vertical components of the electric field surrounding the eyeball caused by the shifting corneO-retinal standing potential.
 15. A process as in claim 1 and further including the initial step, prior to commencing the initial determination of the subject''s instantaneous location of direction of gaze, of subjectively obtaining a refractive correction of the eye of the subject.
 16. A process as in claim 1 and further including the initial steps of determing, under machine control, which eye of the subject is being tested and selecting, in response to such determination, the pattern of presenting said test stimuli.
 17. A process as in claim 1 wherein translating the test field is performed by applying a pure translation to preselected test point coordinates having a fixed coordinate location relative to the direction of gaze of the subject.
 18. A process as in claim 17 wherein the test screen is planar and further including the step of modifying the stimulus value of the test stimuli in accordance with the amount and direction of translation of the test point coordinates.
 19. A process as in claim 18 wherein said test stimuli are spots of light and said modifying step comprises computing the stimulus value B1 of a spot of light at a translated test point in accordance with the expression
 20. A process as in claim 1 further including the step of communicating an alarm signal and ceasing presentation of said test stimuli if the location of the subject''s direction of gaze deviates by a preselected limiting amount from said predetermined point in said test field.
 21. A process as in claim 20 further including the step of resuming the presentation of said test stimuli when the direction of gaze of the subject returns to within said preselected limiting amount from the reference point in said test field.
 22. A process as in claim 1 wherein said test stimuli are each initially presented at a selected location on said test field and then moved, relative to the test field and under machine control, in a certain direction.
 23. A process as in claiam 22 wherein said test stimuli are spots of light and further including the step of determining when the subject perceives each spot of light.
 24. A process as in claim 23 wherein said spots of light are each initially presented at a location on the test field which is outside the visual field of the subject and then moved toward the visual field until the subject perceives the spot.
 25. A process as in claim 24 wherein the speed at which the spots of light are moved is varied as a function of eccentricity from the fixation spot.
 26. A process as in claim 24 further including the step of determining the location on the test field at which the subject perceives each spot of light.
 27. A process as in claim 23 wherein the location determining step includes the steps of: the subject indicating perception of a spot of light by operating a manual device, stopping movement of the perceived spot in response to the operation of the manual device, and determining the location on the test field where the spot was stopped.
 28. A process as in claim 27, further including the step of determining an adjusted location on a path over which a spot of light moved prior to being stopped, the distance of said adjusted location from the location at which the spot was stopped being a function of the speed of movement of the spot multiplied by the reaction time of the subject.
 29. A process as in claim 23 wherin said spots of light are initially presEnted at spaced locations about the perimeter of the test field and then moved toward the location on the test screen of the direction of gaze of the subject.
 30. A process as in claim 29 wherein spots of light are initially presented at locations about the perimeter of the test field on either side of imaginary vertical and horizontal lines which divide the test field into four quadrants.
 31. A process as in claim 29 further including the steps of a. determining, for two spots of light which move along adjacent paths, the locations at which the two spots are perceived by the subject, and b. presenting and moving another spot of light in a path which is substantially perpendicular to a chord extending between the two locations.
 32. A process as in claim 31 wherein the perpendicular path is commenced a predetermined distance from the chord toward the perimeter of the test field and a spot of light is moved from the point of commencement toward the chord.
 33. A process as in claim 31 wherein steps (a) and (b) are repeated for each pair of spots of light which move along adjacent paths until the locations at which each such pair are perceived by the subject are within a predetermined distance of each other.
 34. A process as in claim 23 wherein said spots of light are each initially presented at a location on the test field within a previously detected scotoma of the subject and then moved consecutively in a plurality of directions from the location until the subject perceives the spot of light.
 35. A process as in claim 34 wherein the spots of light are moved consecutively in four directions from the location, each of said four directions being oriented at least 90* from the other directions.
 36. A process as in claim 35 further including the step of determining the location on the test field at which the subject perceives each spot of light.
 37. A process as in claim 36 further including the steps of determining, for two spots of light which move along adjacent paths, the locations at which the two spots are perceived by the subject, and presenting and moving another spot of light in a path which intersects substantially at a right angle a chord extending between the two locations and which commences on one of the paths traversed by one of the previously moved spots of light.
 38. A process as in claim 22 wherein said spots of light are presented on a planar screen and moved in accordance with velocities defined in terms of a Cartesian coordinate system.
 39. A process as in claim 22 wherein said spots of light are presented on a hemispherical screen and moved in accordance with velocities defined in terms of a spherical coordinate system. 